Method of artificially coloring roofing granules



UNITED STATES PATENT OFFIE METHOD OF ARTIFICIALLY COLORING ROOFING GRANULES Stephen G. Wright, Chicago, Ill.

No Drawing. Application November 20, 1933, Serial No. 698,931

6 Claims. (01. 91-70) This invention relates to amethod of artificially the order of 1500 F. until the cullet has fused coloring roofing granules. and formed a glaze upon the surface of the gran- Roofing granules are made from a great vaule. The pigment will attach itself to the glaze riety of natural rocks such as slate, quartz, granite in irregular patches, but the effect of the whole and trap, and also from various burned earthy upon the eye is homogeneous; that it, a group of 5 material such as, brick, tile and sanitary potrock granules, coated and pigmented in this mantery. Any stone or baked earthy material may be ner, will appear uniform in color, although, upon I used as the base material of this invention, proclose inspection, it will be observed that the pigvided that it will stand an ordinary ceramic temment covers only irregular portions thereof.

perature, say, of 1500 F. or more, and provided The cullet is composed of broken scrap glass of 10 also that the impurities of the basic material widely varying melting points, but it is necessary, thereof, such as iron, sulphur, lime or the like, in selecting cullet for this purpose, only that the are not in sufficient quantity to destroy under major portion of the whole be of sufficiently low heat the brilliancy of the various coloring matemelting point to fuse at the desired treating temrials which must be used. Heretofore such rock perature, say, 1500, F. or more Those particles 5 particles or granules have been glazed with silwhich do not melt become embodied in the melted icate glazes and colored powdered glass has likeglazed portion and provide a roughened or wise been used in connection therewith. Howtoothed surface upon the granules which causes ever, expense is a primary factor -in the producthem to adhere more firmly to the asphalt surtion of such granules, and the cost of colored face of the roofing. This presents an appreciable 20 glass makes the use of this product wholly imadvantage over ordinary glazed granules which practicable. are less adherent than unglazed granules. The

There is now available, however, at low cost, effect of the unmelted portions may be increased, waste broken glass, of indeterminate color and if desired, by adding an additional quantity of composition, which is known to the trade as non-fusible material such as ground quartz, or 25 cullet. It has now been discovered that this even fine sand, to the cullet, to supply the desired material may be ground to a powder, mixed roughening effect.

' with roofing granules to which it is caused to ad- The addition of various fluxing agents, such as here, an inexpensive pigment added and the borax,'lead oxide and the like, provides greater whole heated. In order to affix the cullet to the spreading power or covering ability to the cullet, 30 rock particles prior to the heat treatment, a provides a more complete covering for the surtemporary adhesive material is used. After the face of the granule, and a better and more even heat treatment, the cullet itself fuses to a glaze distribution of. the coloring pigment. and apparently no adhesive is necessary. The intensity and shade of the pigment may In accordance withthis invention, cullet may be controlled by the addition of non-fusible ma- 35 be ground to afineness of preferably 95% through terials, such as barytes, pulverized silica, or pula' ZOO-mesh standard screen, and the resulting verized stone, of any character or color. powder is mixed with an adhesive material such In accordancewith this invention, 20 pounds as glue, glucose, varnish, shellac, resin, sodium of chrome oxide may be' added to 100 pounds of v 40 silicate, or any other material which will cause powdered cullet and 50 pounds of commercial 40 the pulverized cullet to adhere to the rock parsilicate of soda (40 B.) with 50 pounds of water, ticles when mixed with them and which will dry and the whole mixed with one ton of pulverized under ordinary drying conditions, or which will quartz. The mass is then heated at 1600 F. until be absorbed into the granule itself to such an ex- 2. glaze has been produced.

tent that the granules do not adhere to each The silicate of soda may be replaced by equiva- 45 other. lent amounts of other adhesives such as liquid A coloring matter is likewise added to the powglue, flour, sugar, varnish, and the like. If wader and adhesive, either in solution or in pigter-immiscible materials such as varnish are ment form. Various pigments, such as iron oxused, a heavy naphtha solvent may be used in ide, chrome oxide, and the like, may be used, proplace of the water. 50

viding they will withstand the necessary heating- The quartz may be replaced by other rock such temperature. as rhyolite, granite, trap rock, slate, gravel, and

The pigmented and powdered cullet is mixed the like. with the rock granules and the whole is heated, I Other examples of the invention are as follows: for example, in a rotary kiln to a temperature of 1. pounds of pulverized cullet, 20 pounds 55 of flour and 18 pounds of chrome oxide were mixed with 140 pounds of water and with 1 ton of rhyolite, and the whole was then heated at '1800 F. until a glaze had been produced.

of chrome oxide, 5 pounds of glue, 120 pounds of water and 1 ton of green slate were thoroughly admixed and burned at 1550 F. v

4. Eighty pounds of pulverized cullet, 18 pounds of chrome oxide, 3 pounds of glue, 75 pounds of water and 1 ton of quartz were mixed and heated at 1600" F.

5. Fifteen pounds of iron oxide, 30 pounds of heavy naphtha, 30 pounds of gloss oil (varnish), 120 pounds of pulverized cullet and 1 ton of buff gravel were mixed and heated at 1550 F.

6. One ton of trap rock, pounds of water and 10 pounds of borax were mixed and dried. Then 18 pounds of chrome oxide, 40 pounds of water, pounds of sodium silicate (40), and pounds of pulverized cullet were added and the whole burned at 1550 F.

The foregoing detailed description has been given for cleamess of understanding only, and no unnecessary limitations should be understood therefrom, but the appended claims should be construed as broadly as permissible, in view of the prior art.

I claim:

1. The method of coloring rock granules for roofing compositions, which comprises admixing high melt point powdered cullet, low melt point powdered cullet and adhesive material, a pigment, and a large excess of rock granules, whereby said cullet and pigment are caused to adhere temporarily to said particles, and heating the mixture to a temperature above the melting point of the low melt point cullet, whereby said low melt point cullet forms a glaze upon said rock particles in which said pigment and said high melt point cullet are imbedded.

2. As a new article of manufacture, adapted to be used in connection with asphalt roofing, rock particles having thereon a fused cullet glaze, said glaze comprising a major portion of fused low melt point cullet, having imbedded therein a color pigment, and a minor portion of projecting irregular particles of unfused high melt point cullet.

3. The method of coloring rock particles for roofing composition, which comprises admixing a major portion of low, melt point powdered cullet, a minor portion of high melt point powdered cullet, adhesive material, a pigment, and a large excess of, rock granules, whereby said cullet and pigment are caused-toadhere temporarily to said particles, and heating the mixture to a temperature above the melting point of the low melt point cullet, whereby said low melt point cullet forms a glaze upon said rock particles in which said pigment and said high melt point cullet are imbedded.

4. An article as set forth in claim 2, in which the pigment is iron oxide.

5. An article as set forth in claim 2, in which the pigment is chrome oxide.

6. An article as set forth in claim 2, in which the rock particles are quartz and the pigment is chrome oxide.

' S'I EPHEN G. WRIGHT. 

